Depending upon the location and requirements, wind energy plants must be provided with a specified flight navigation device. In Germany, they must be marked for example by an obstruction light, a hazard beacon, a blade tip obstruction light or Feuer W rot (=“W red light” standard) in accordance with their overall height (see Nachrichten für Luftfahrer [News for Airmen], Part I, Deutsche Flugsicherung [German Air Traffic Control], January 2005). While hazard beacons have a light intensity of more than 1=2000 cd, the light intensity of obstruction lights is only at least 1=10 cd and amounts to only a fraction of the light intensity of hazard beacons. The navigation lighting in wind energy plants is normally always designed in pairs and in a redundant manner.
A flight navigation device for a wind farm is known from EP 1 282 888 B1, in which the individual wind energy plants are equipped with one flight navigation device in each case and the wind farm control comprises a synchronization unit which synchronizes the lighting means in such a way that the lighting means of the various wind energy plants are switched on and off simultaneously.
It is the object of the invention to make available a method of operating a wind energy plant and a wind energy plant which operates with such a method, the method and wind energy plant being more reliable.
It is also the object of the invention to make available a method of operating a wind farm and a wind farm, the method and wind farm being more reliable.
The object is attained with respect to the first method by a method specified in the introduction and having the characterizing features of claim 1.
In this case, flight navigation devices are understood as being both hazard beacons and obstruction lights. Modern flight navigation devices usually have the lighting means in the form of LEDs. As compared with conventional filament lamps or discharge lamps, LEDs require little maintenance and are wear-free. A drawback of LEDs, however, is that they have only a very limited radiation spectrum. By way of example, the red LEDs to be used for the flight navigation devices radiate wavelengths in a range of between λ=610 to 750 nm. LEDs radiating in the visible spectrum range are referred to below as VIS LEDs. In this way, the demands made upon the marking of obstructions are indeed met in the visible light spectrum. Night flights, in particular of helicopters, are usually not carried out in the region of wind energy plants or wind farms, but the pilots in question usually fly around these obstructions. Under certain circumstances, however, for example during the rescue of stranded persons in offshore wind farms, it may be necessary to have to fly at night in the vicinity of wind farms or into the wind farms. Night flights, in particular night flights of helicopters, are frequently carried out with night-vision devices. The night-vision devices detect the light spectrum in the near infrared range (NIR) and convert this into visible light. In this case the NIR range is in wavelengths of from λ=750 nm to λ=1500 nm. The operating range of the night-vision devices covers, depending upon the device, different spectral ranges in the NIR in this case, but it does not extend into the visual spectral range of from λ=350 nm to λ=750 nm. Since the spectral range of the LED flight navigation devices radiating only in the visual range does not correspond to the detection range of the night-vision devices, it is possible for wind energy plants to be overlooked during night flights, and dangerous situations can arise.